docs: def reset(self):
      """Reset the estimates of mean and variance.
  
      Resets the full state of this class.
  
      Returns:
        Operation.
      """
      with tf.name_scope(self._name + '/reset'):
        return tf.group(
            self._count.assign(0),
            self._mean.assign(tf.zeros_like(self._mean)),
            self._var_sum.assign(tf.zeros_like(self._var_sum)))